DE 197 03 504 A1 discloses an auxiliary chassis for a motor vehicle, serving to enhance a transverse rigidity of the vehicle. The auxiliary chassis comprises side parts, each in turn comprising at least two points of articulation for swingable articulation of a transverse or oblique caster connected to a wheel mount and a monocoque transverse member arranged between the side parts, which, at installation of the auxiliary chassis in the motor vehicle, is offset from a line connecting the centers of the wheels. This auxiliary chassis is distinguished in that the cross-section of the transverse member comprises a half-open profile whose opening, at installation of the auxiliary chassis in the motor vehicle, points substantially in the direction opposed to the line connecting the wheel centers. The transverse member, when used in the front axle region, may serve as a bottom girt to accommodate an electrohydraulic pump system, an ABS/EDS device, and/or a standing heater. Also, the bottom girt may be utilized for attachment of hydraulic lines of the front brake circuit or other cabling.
DE 3,522,447 A1 shows a lengthwise member of a truck for the front part of a motor vehicle. A motor vehicle comprises two such lengthwise members, extending directly behind the bumper, which they support. The lengthwise members are connected in the front-end portion to a transverse member and in their rear end portion to a posterior transverse member. The forward one-third of the lengthwise member is releasably attached to the rear portion of the lengthwise member, so that the two anterior portions of the lengthwise member together with the transverse member form a structure capable of being pre-assembled to form a unit, with other vehicle components, such as the bumper, the radiator, a condenser, an air conditioning system, a metal plate for spotlights etc.
With the auxiliary chassis according to DE 4,129,538 A1 and the structure according to DE 3,522,447 A1, portions of the front carriage of a motor vehicle may be preassembled and installed as a unit in the bodywork of the vehicle. However, there is a considerable need for an additional, more efficient assembly of the vehicle parts, for assembly outlay is one of the substantial cost items in the production of a motor vehicle.
The object of the invention, then, is to configure a motor vehicle in such manner that assembly is substantially simplified and accelerated.
The full auxiliary chassis according to the invention serves to accommodate and suspend the engine, the transmission and other auxiliary parts, such as an electrohydraulic control device, a radiator, a guidance transmission, an ABS/EDS device or the like. The full auxiliary chassis includes a rear transverse member, a front transverse member, and two side members connected to form, a closed horizontal generally rectangular structure. This structural unit may be installed in the motor vehicle in the preassembled state, with engine, transmission and auxiliary equipment. This reduces assembly outlay considerably, since the complete powerplant with all auxiliaries can be preassembled in a module, this preassembly taking place independently of any passenger car assembly line. The prefabricated module is then placed in the vehicle and connected therewith in a single operation.
The result is a definite reduction of manufacturing time on the passenger car assembly line and a considerable reduction of costs. The productivity of a motor vehicle plant is thereby increased.
A further essential advantage of preassembling such a module on the full auxiliary chassis is that at preassembly, all parts to be assembled are readily accessible, since they are not covered by bodywork parts, thus improving quality. Specifically, robots may be employed to process the connections, performing these operations very dependably and economically. This permits a further reduction of costs with simultaneous improvement of quality.
In a preferred embodiment of the invention, the side members are connected to the transverse members by bolts, so that in the event of damage to a transverse or lengthwise member or to a unit connected to these, only a single transverse or lengthwise member, as the case may be, need be removed, and the corresponding transverse or lengthwise member or unit connected thereto replaced.
In another preferred embodiment of the invention, the front transverse member is of a generally horizontal U-shaped configuration in top view, with a long traverse section and two shorter legs extending generally in the lengthwise direction of the vehicle. The legs are integrally connected to the traverse. Thus, in the first place, in maintenance of the vehicle, a front subunit, bearing for example a radiator, intake air cooler and condenser, may be pulled from the engine compartment of the vehicle, and in the second place, the transverse member forms a stable unit that, in a collision, will transmit the energy of deformation to the lengthwise members, which will then deform correspondingly. In particular, the two legs may serve as deformation parts and accommodate a great deal of energy of deformation within a short travel. The auxiliary chassis according to the invention, therefore, provides additional collision protection in addition to the bumper itself.
The invention will now be illustrated by way of example with reference to the accompanying drawings.